I doubt it would be as hellish as you make it out to be. I for one would love the opportunity to enjoy a severely long life. Unfortunately I seem to be in the majority here. It's frustrating because so many people seem to think it's such a horrible thing I fear progress is going far too slow to achieve any kind of immortality in my life time.

I would love to see a game like this be actually fun to play. I've seen so many "educational" games that are just plane boring because they try to mix education and fun without actually integrating them. Here's hoping this one works out.

No, it does not exist. All of these effects that are attributed to dark matter are all actually due to the fact that gravity does not actually travel at the speed of light. In fact, gravity slows down as it travels. This is why there appears to be more gravity at the edges of galaxies, and even at the edges of galaxy clusters. I also explains why we have such expansive gaps between galaxy clusters.

I had your problem for the longest of times too. No one seemed bothered that this given explanation was no different than a classical example. And it seems most people don't ever think about it to the level that you have. (So congratulations I guess).